gstv4l2tuner: return NULL if no norm set

If the video4linux device supports norms but has no norm set, norm is
returned as an uninitialized variable after the ioctl call, leading to
gst_v4l2_tuner_get_norm_by_std_id() returning a random norm from the
supported norms. Catch this case and instead return NULL to indicate
that no norm is setup.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1625>

diff --git a/subprojects/gst-plugins-good/sys/v4l2/gstv4l2tuner.c b/subprojects/gst-plugins-good/sys/v4l2/gstv4l2tuner.c
index c08b2ca..d70f9c2 100644 (file)
--- a/subprojects/gst-plugins-good/sys/v4l2/gstv4l2tuner.c
+++ b/subprojects/gst-plugins-good/sys/v4l2/gstv4l2tuner.c
@@ -181,7 +181,8 @@ gst_v4l2_tuner_get_norm (GstV4l2Object * v4l2object)
   /* assert that we're opened and that we're using a known item */
   g_return_val_if_fail (GST_V4L2_IS_OPEN (v4l2object), NULL);
 
-  gst_v4l2_get_norm (v4l2object, &norm);
+  if (!gst_v4l2_get_norm (v4l2object, &norm))
+    return NULL;
 
   return gst_v4l2_tuner_get_norm_by_std_id (v4l2object, norm);
 }